The long term goal of this research is to investigate the feasibility of assisted liquid (FC-80) ventilation as a therapeutic method for resuscitating neonates with RDS and those with severe aspiration syndrome. The short term goal is to investigate the implications of liquid ventilation using in utero stressed newborn lambs with the "RDS" like disease to ascertain a deeper insight into the pathophysiology of the disease. Liquid ventilation feasibility studies in fetal lambs with the "RDS" like disease will make available the following pathophysiological data: (1) Molecular transport mechanisms (O2, CO2, protein, etc.) during liquid ventilation. (2) Pulmonary mechanics of the liquid filled lungs. (3) Lecithin synthesis by analysis of liquid samples. (4) Oxygen toxicity effects on lung tissue. (5) Recovery and survival statistics following liquid ventilation.